1. Field of the Invention
The present invention relates to a robot control unit for controlling a tandem arc welding system that performs arc welding of a V-groove, an L-groove, or a groove like that by advancing a welding torch having two electrodes along a weld line while weaving the welding torch right and left using a robot; and an arc-sensor control method using this unit.
2. Description of Related Art
Usually, the tandem arc welding system automatically performs welding by using the robot control unit and the like, wherein teaching of an operation trajectory is previously performed, and a stored teaching trajectory (weld line) is reproduced, that is, so-called arc-sensor control is performed for welding operation. Here, the arc-sensor control refers to processing for a weaving center trajectory of a welding torch to correctly follow a teaching trajectory. As a related art on arc-sensor control during arc welding, JP-A-2005-254242 is given. The JP-A-2005-254242 describes a robot control unit for controlling a tandem arc welding system that detects quantity of welding state of each of two electrodes (leading electrode and trailing electrode) attached to a tip of the robot, corrects a trajectory of the robot in a horizontal direction based on the quantity of welding state of one of the leading and trailing electrodes, and corrects the trajectory of the robot in a vertical direction based on the quantity of welding state of the other electrode.